allow to select CPU level = 5 from .bochsrc even when Bochs is compiled with CPU_LEVEL=6

git-svn-id: svn://svn.code.sf.net/p/bochs/code/trunk@11679 6c8e4198-a580-4521-a02f-c9ae86df1db9
do not recognize MTRR MSRs when mtrr is not enabled

git-svn-id: svn://svn.code.sf.net/p/bochs/code/trunk@11680 6c8e4198-a580-4521-a02f-c9ae86df1db9